Scientists develop tool to trace metabolism of cancer-fighting tomato compounds

The University of Illinois scientists who linked eating tomatoes with a reduced risk of prostate cancer have developed a tool that will help them trace the metabolism of tomato carotenoids in the human body. And they've secured funding from the National Institutes of Health to do it.

"Scientists believe that carotenoids—the pigments that give the red, yellow, and orange colors to some fruits and vegetables -- provide the cancer-preventive benefits in tomatoes, but we don't know exactly how it happens," said John W. Erdman, a U of I professor of human nutrition.

The researchers will use isotopic labeling of three tomato carotenoids with heavier carbon atoms than are commonly seen in nature, which will allow tracking of the tomato components' absorption and metabolism in the body, he said.

"We have two questions we'd like to answer. First, are the carotenoids themselves bioactive, or are their metabolic or oxidative products responsible for their benefits? Second, is lycopene alone responsible for the tomato's benefits, or are other carotenoids also important?" he said.

Previous Erdman animal studies have shown that whole tomato powder, which contains all of the fruit's nutritional components, is more effective againstprostate cancer than lycopene alone.

"Lycopene, which gives the fruit its red color, has received a lot of attention—it's even advertised as an ingredient in multivitamin supplements, but two little-known colorless carotenoids, phytoene and phytofluene, probably also have benefits," said Nancy Engelmann, a doctoral student in Erdman's laboratory who helped to develop the new method.

Engelmann learned to optimize the amount of carotenoids in tomato cell cultures by treating already high-achieving tomato varieties with two plant enzyme blockers. The best performers were then chosen for culturing and carbon-13 labeling, she said.

The scientists grew tomato cells with non-radioactive carbon-13 sugars, yielding carbon molecules that are heavier than the 12-carbon molecules that exist elsewhere, Erdman said.

"These heavy carbon molecules are then incorporated into the carotenoids in the tomato cell cultures. The result is that researchers will be able to track the activity of lycopene, phytoene, and phytofluene and their metabolites," he said.

Thanks to NIH funding, U of I researchers and colleagues at The Ohio State University are preparing to use this new tool to study carotenoid metabolism in humans.

"It's exciting that we now have the means to pull off this human study. It's work that should move us forward in the fight against prostate cancer," he said.

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Chemists design molecule that responds to stimuli

A cartoon representation of reversible organization from synthetic

 lipid-like molecules to form cell-like structures (called vesicles) 

upon change in temperature. 

The cell like structures cluster together similar to toad eggs 

or Caviar-like morphologies upon 

maintaining a particular temperature.

The venus flytrap plant captures its prey when it senses the presence of an insect on the tips of its leaves. An amphiphilic molecule designed by chemists at The City College of New York acts in a similar manner by changing its structure when heated slightly and, then, reverting to its original form when cooled.

The finding, reported in the journal Angewandte Chemie, points toward the possibility of designing adaptive soft materials in the lab that take their cues from how nature responds to stimuli, said Dr. George John, associate professor and corresponding author.

Professor John and colleagues designed the molecule, which has both water-adhering and water-repelling ends, from cardanol, a naturally available material found in cashew nut shell liquid. When mixed with water, the molecules formed a self-assembled structure called a micelle with a water-adhering exterior and water-repelling interior.

Warming the micelles to 50 degrees Celsius caused them to take on a three-dimensional structure known as a vesicle that was larger – 200 – 300 nm in diameter – and viscous, much like oil. "The molecules would stick together, similar to caviar," Professor John said. "When we touched the material with a glass rod, we could draw it out in a thin strand, much like glue."

Allowing the material to cool resulted in the molecules reverting to their original micellar structure. When they were reheated, they would again take on the viscous form.

The change in structure resulted because, while heating caused the micelles to rearrange, they began to interlock in a bi-layer arrangement and eventually undergo curvature. Directional hydrogen bonding of the amide linkages and stacking of the aromatic ring groups, further stabilized the assembly.

The objective of the research is to study responsive systems, Professor John said. "If we can understand the influence of saturation at the bi-layer stage, we can regulate the adaptive response to stimuli." This will require investigating the number of micelles needed in a mixture and where they need to be positioned.

physorg

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Snake fangs evolved from groovy teeth

A SET of 200-million-year-old teeth from a beast related to dinosaurs and crocodiles has shed light on how snake fangs evolved. They support the idea that venom canals inside fangs evolved from grooves on the tooth surface.

The late Triassic reptile Uatchitodon is known only from its teeth, which resemble tall, serrated crocodile or dinosaur teeth. Several have been found, and the two youngest ones, dating from 220 million years ago, have what look like venom canals. An older set have grooves of different depths but no canals. Until now it was unknown whether the variations reflected evolutionary changes, different stages of tooth development, or even teeth from different positions in the mouth.

Now Jon Mitchell from the University of Chicago thinks he has cracked it. He and his colleagues discovered 26 Uatchitodon teeth in North Carolina. Their age places them between the other two sets, and lining up all the teeth shows how grooves that initially formed at the surface gradually lengthened and deepened until they became enclosed canals .

Snake fangs probably evolved independently of Uatchitodon, says Mitchell, but the sequence of events was most likely similar. Bryan Grieg Fry from the University of Melbourne, Australia, is convinced this is the case, and says the fossil series is "fantastic".

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Green machine: Bugs and sparks turn salty water fresh

Mixing bacteria with drinking water sounds like a recipe for an upset stomach. But a bug-powered desalination cell that takes salt out of seawater may cut the cost of quenching the world's thirst.

With one-third of the planet's population lacking sufficient drinking water, governments are increasingly looking to desalination to produce fresh water from seas and estuaries.

However, conventional desalination plants consume large amounts of energy. For instance, they use reverse osmosis, in which water is forced at enormous pressure through membranes that screen out salt. This means there's keen interest in less energy-intensive approaches.

One that's recently been explored uses bacteria that generate electrical power by eating organic matter. If these bacteria feast on domestic sewage in an "anode" chamber, they generate electrons that can pass into a circuit while releasing protons. To balance the now positively charged sewage solution, negative chloride ions squeeze through a membrane from an adjacent chamber containing salty water that is to be desalinated.

Meanwhile the electrons are delivered to a third, "cathode" chamber on the opposite side of the desalination chamber. The cathode chamber is also filled with a saltwater solution. Here, the electrons react with hydrogen ions in the solution and oxygen from the air to form water. To balance the negative charge caused by the loss of positive hydrogen ions, sodium ions pass from the central saltwater chamber into the cathode chamber via another membrane. With time, the salty water in the central chamber becomes fresher.

Tang trouble

But such a device is relatively inefficient, says Bruce Logan at Pennsylvania State University in University Park: as the organic content in the waste water falls, the voltage produced by the bacteria drops and pulls fewer ions out of the saline water, leaving it with a salty tang. Flushing the anode with more sewage is one option, but Logan's team are keen to squeeze as much use from each batch of dirty water as possible.

They have has developed a simple solution: boost the voltage from the bacteria with an external power source to make up any deficit. Furthermore, if the electrons react only with water at the cathode, they generate hydrogen gas – which contains enough energy to fuel the extra voltage requirements.

The team filled the central chamber of their cell with brackish water containing 5 grams of sodium chloride per litre, as might be found in an estuary, and applied a voltage of 0.55 volts to the setup. Over several hours, the salinity of the salt water dropped by 68 per cent to 1.6 grams of salt per litre. A standard microbial desalination cell stalls when the salinity reaches 40 to 60 per cent – or 2 to 3 grams of salt per litre.

By varying the voltage added to the system as the reaction continues – and by using more water in the anode and cathode chambers than in the saltwater chamber – Logan says it should be possible to reduce the salinity to the 0.8 grams of salt per litre typical of drinking water.

"It is likely people would still want some sort of added treatment to ensure good quality water, and thus we expect a downstream reverse osmosis unit to still be used," he says, but using the new cell as a "pre-treatment to greatly reduce salt concentrations" should help to substantially reduce the energy needed to obtain fresh water from the sea.

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Physicists say early universe like liquid

European researchers at CERN's Large Hadron Collider say experiments show the very early universe was not only very hot and dense but behaved like a hot liquid.

By smashing lead nuclei together at high energies, they've generated incredibly hot and dense sub-atomic fireballs, recreating the conditions that existed in the first few microseconds after the Big Bang, ScienceDaily.com reported.

Scientists say temperatures of over 10 trillion degrees are being created in these mini big bangs.

At these temperatures, normal matter is expected to melt into an exotic, primordial 'soup' known as quark-gluon plasma.

And scientists say their results suggest "melt" is the right word.

"These first results would seem to suggest that the universe would have behaved like a super-hot liquid immediately after the Big Bang," David Evans of the University of Birmingham's School of Physics and Astronomy in the United Kingdom says.

This contradicts a number of theoretical physics models that predicted the quark-gluon plasma created at these energies would behave like a gas.

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Single drop of blood could reveal age!!

Blood drop - نقطة دم

Dutch researchers say they've developed a way to tell a person's approximate age from one drop of blood, a test that could be used in crime investigation.

Scientists at Erasmus University Medical Center in Rotterdam say as a forensic technique it could be used to revive police investigations that have hit a dead end, AAAS ScienceMag.org reported Monday.

The blood-age test relies on a peculiarity of T cells, immune cells in the body that recognize and fight microbial infections.

As T cells develop, they modify their DNA to recognize a wide variety of bacteria and other pathogens.

In the modification, some DNA is left over that is useless to the T cell, which discards it, researchers say.

The amount of discards in the body can be used to estimate a person's age since people produce fewer and fewer T cells as they get older.

"We take advantage of this waste product" in estimating a person's age from a sample of blood, forensic molecular biologist Manfred Kayser says.

The researchers found a correlation between the number of T cell DNA fragments and age, allowing them to pinpoint how old a person was to within plus or minus 9 years.

It's a wide range but enough to place suspects into generational categories, which could be helpful to police, Peter de Knijff, head of the forensic laboratory at Leiden University Medical Center in the Netherlands, says.

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A tattoo monitor health!!!!

A sensor to be injected into the skin just like a tattoo that measures sodium concentrations in the blood has been developed by US scientists. The sensor could be used to monitor diseases or warn against dangerously low sodium levels during exercise. 

Heather Clark from Northeastern University, Boston, and coworkers made plastic nanobeads that fluoresce to different extents with changes in sodium levels. The beads are coated with a biocompatible polymer and are injected just under the skin to allow the fluorescence to be monitored easily. 

Technology for determining the amount of sodium in the bloodstream has been available for some time. However, it requires a blood sample from the patient, which limits the measurements to isolated time points. This is a problem for understanding a condition called hyponatremia, where sodium concentrations in blood serum are lower than normal. Hyponatremia can occur after certain types of surgery, with brain trauma or tumours, and has been found in endurance athletes. 

The team tested the sensor by injecting it into the skin of mice and analysing the fluorescent images produced. Clark says she hopes that the final product will be a safe and minimally invasive sensor. 'We are currently developing a more biodegradable sensor,' she explains, 'to inject into the epidermis (the top layer of the skin) that falls off after seven days, so it would be like a non-permanent tattoo.' Clark envisions the sensor beads could be placed into the fingertip and monitored in much the same way that blood oxygen concentrations are in hospitals - with a pulse oximeter clipped to the finger. 

'The technique has potential, however there is still some way to go,' says Ibtisam Tothill, an expert in analytical biochemistry at Cranfield University, UK, who adds that it must be proven to be quantitative before it can be applied to humans. Clark agrees that this is the next step and the group hope that it will be relatively straightforward to demonstrate the applicability to real situations. In the future, Clark also hopes to develop a nanoclinical analyser capable of measuring more than one analyte. 
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Rise of the micro machines

Microjet engines called microbots that can transport cells within a fluid to any desired location have been developed by German scientists.

Manipulating nanomachines to transport biological matter in the body has been a challenge until now. Samuel Sanchez from the Institute for Integrative Nanosciences in Dresden and colleagues have shown that by using a magnet, it is possible to navigate a microbot towards a specific cell within the body, pick it up from point A and transport it to point B. 

Taking their inspiration from Mother Nature, the team looked at existing biological motor proteins - flagellae, which are tail-like projections that protrude from certain cells to help them move independently, and kinesin, a more complex motor protein found in eukaryotic cells that aids cell movement during mitosis and meiosis. Both are powered by chemical fuel and produce mechanical energy. 

Sanchez's team was able to transport multiple micro-objects in fluid, such as colloidal microparticles and metallic nanoplates. They had also reduced the toxicity of the peroxide fuel using the enzyme catalase, which breaks down the peroxide and releases oxygen bubbles that propel the microbots. 'The next step was to demonstrate that our microbots can transport biological material such as cells,' explains Sanchez. 

To do this, the group made small machines made up of hollow tubes containing a thin layer of platinum on the inside. They found that the machines moved independently in a peroxide solution when controlled externally by a small magnet manipulated with a joystick. The microbots can be directed towards suspended cells in solution, where they suck them up through the tube and transport them to the desired location. They released the cells from the tube by rapidly turning the magnet.

'This groundbreaking discovery by the Sanchez group opens up new avenues for highly important biomedical and bioengineering applications,' comments Martin Pumera, an expert in nanotechnology and microfluidics at Nanyang Technological University, Singapore. 'It is truly a dream come true.'

Sanchez and his team hope that in the future their microbots could perform visionary tasks within the body. 'I would like to see our microbots swimming inside the bodies of animals, delivering drugs to required locations, for example, in the vicinity of cancer cells or replacing diseased cells with healthy ones.'

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Neutral positronium scatters like a charged particle

Positronium beamline: where are the positrons hiding?

Positronium is the atom-like bound state of an electron and its antiparticle the positron – and therefore has no net electrical charge. But physicists in the UK are scratching their heads after finding that positronium interacts with matter as if it were a lone electron, with the mass and positive charge of the positron seemingly invisible. This surprising discovery will spur researchers to find an explanation, and may have consequences from medicine to astrophysics.

Positronium is often regarded as the lightest neutral atomic species. Like a normal hydrogen atom, its nucleus is orbited by a lone electron, but the proton of the nucleus itself is replaced by the positron.

Positronium is an important entity in various disciplines. In medicine, for example, positrons are used to image chemical-reaction pathways inside living cells, in a technique known as positron emission tomography (PET). Yet over 80% of the crucial gamma rays generated in PET scans are from decaying positronium. Meanwhile, in astrophysics, decaying positronium accounts for over 90% of the gamma rays coming from the Milky Way's centre.

Scarcity of scattering knowledge

Since positronium lives long enough to scatter off other matter before decaying, scientists involved in such disciplines need to understand its scattering properties. Unfortunately, both theory and experiments on these have been hard to come by.

Now, Gaetana Laricchia of University College London and colleagues have recorded the first widespread velocity data for positronium scattering off a variety of atoms and molecules. In their experiment, they use electric and magnetic fields to guide positrons emitted from sodium-22, a radioactive source, to a gas cell. Some of the positrons pick up an electron from the gas, creating a beam of positronium that travels toward a gas target. The researchers used 10 different targets to scatter the positronium, including helium, nitrogen, oxygen and krypton.

The results were not what they expected. Despite positronium being neutral and twice the mass of an electron, its scattering cross section – a measure of the interaction probability as a function of velocity – always resembled an electron on its own.

'Spectator' particle?

Laszlo Sarkadi, a nuclear physicist at the Hungarian Academy of Sciences who has previously studied positronium scattering, says the discovery will prompt physicists to examine the detailed dynamics of the scattering, which he thinks cannot be approximated, like other collision systems, to a two-body interaction. Nonetheless, be believes the likely solution is that the positron in the positronium is merely behaving as a "spectator" particle. "The different behaviour of the electron [could be] explained by the polarization of the target during the collision," Sarkadi adds.

Laricchia agrees that the positronium's electron is somehow dominating the interaction, but says: "The reason is not yet known, and we hope that our work will stimulate further research."

physicsworld 

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Flexible metamaterial springs to life!!

Meta-flex springs to life

Physicists in the UK have made a new kind of flexible material that could enclose objects to render them and it invisible. Although unlikely to be of much use when it comes to shielding people and other large objects, it could, say the researchers, nevertheless hide small items and make contact lenses more powerful.

Over the last few years physicists have shown how to hide objects by placing them inside so-called invisibility cloaks. These cloaks are made from metamaterials – artificial, engineered materials that have unusual electromagnetic properties. The first such cloak was made from a cylinder consisting of copper rings placed in concentric circles, and enabled an object placed at its centre to be shielded against microwaves, the radiation flowing around the cloak and continuing along its original trajectory as if the cloak were not there. Researchers have since extended this concept to shorter wavelengths by making ever tinier features within the metamaterials, since the features have to be smaller than the wavelength of light used.

All cloaks to date, however, have used metamaterials rooted in hard substrates typically made from glass or silicon. Andrea Di Falco and colleagues at the University of St Andrews in Scotland have instead created a flexible metameterial, operating at visible wavelengths, which, they say, should give metamaterials a much broader range of practical applications. The inspiration was the kind of flexible electronic circuitry used in laptops to connect the screen to the keyboard, but in this case applied to optical structures.

Introducing Meta-flex

The researchers made their material, which they have dubbed "Meta-flex", by placing a commercially available polymer known as SU8 onto a silicon substrate. They then deposited a 40 nm-thick gold layer onto the polymer and used electron-beam lithography to carve the desired metamaterial features into the gold, before immersing the structure in a suitable solvent to remove the substrate.

The researchers say they have been able to make pieces of Meta-flex as thin as 4 μm and having an area of 40 mm². They tested the electromagnetic response of two different metamaterial configurations, known as nanoantennas and "fishnet" lattice, by exposing the material to a source of white light and then analysing the transmitted light using a spectrometer. They found that the absorption peaks matched those obtained with the equivalent rigid metamaterials, proving, they say, that Meta-flex can indeed function as an invisibility cloak.

Using this new material to carry out useful functions will require mounting multiple layers on top of one another. But doing so, cautions Di Falco’s colleague Thomas Krauss, will not lead to invisibility cloaks of the kind that could be used by real-life Harry Potters. Cloaks made from Meta-flex, he says, can be larger than the nanometre-scale features engraved into the the material but the size of these cloaks is limited by the need for the cloak to have a certain thickness. With a given fraction of the incident light absorbed by each layer, a thick cloak would absorb practically all of the light that fell on it. "We should be able to cloak objects on the sub-micron level," he says. "And as we improve the material we should be able to increase this scale, but I find it hard to think that we will ever be able to cloak large objects".

Better contact lenses

As an example of the kind of object that could be rendered invisible, Krauss suggests electrical cables integrated into clothing. However, he believes that Meta-flex will find more useful applications. For instance, he says, the material could be used to increase the correcting power of contact lenses, making lenses available to people who previously have had to make do with thick glasses. He points out that the ability to bend light is dictated by the variation in refractive index of the media that the light traverses, so making a metamaterial with a refractive index of close to zero creates a ratio of indices approaching infinity and therefore results in an extremely high corrective power. He says that although this principle has been demonstrated previously, it is the manufacture of a flexible substrate that renders it useful for the manufacture of contact lenses.

John Pendry of Imperial College in London, who has pioneered the use of metamaterials, describes the development of the new material as an "interesting and useful advance in metamaterial technology" but "very, very far from achieving a flexible cloak". He points out that as the instantaneous shape of a cloak changes, so too do the electrical permittivity and magnetic permeability needed for invisibility. So a flexible cloak, he says, would require that the metamaterial be not only flexible but also one whose electrical and magnetic parameters can be continuously reconfigured.

Krauss acknowledges this point but maintains that as long as the shape of the cloak doesn't change too much the metamaterial parameters can remain fixed. "For a Harry Potter cloak you would need to do what Pendry is saying, but for the kind of specific applications that we're suggesting you could design a metamaterial of a certain curvature and leave it at that," he says.

physicsworld 

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